1. Field of the Invention
The invention relates to a photographic film assemblage having means for enabling a leading end of a strip of film to be easily retrieved or moved from within a film cassette.
2. Description of the Prior Art
The present invention relates to a photographic film assemblage of the type including a housing having a lighttight exit or passageway through which a leading end of a strip of film is adapted to be moved to the exterior of the housing so as to enable it to be attached to a film advance mechanism of a camera or film processor and, more particularly, to such an assemblage which includes means for retrieving such leading end should it be inadvertently, or otherwise, located within the housing.
Among amateur and professional photographers, one of the most popular film formats is the 35 millimeter size. In the 35 millimeter system, the film is normally carried on a spool within a lighttight cylindrical cassette. Despite its popularity, this system has the disadvantage that, when the cassette is to be removed from the camera, the film must first be rewound into the cassette to avoid exposure to light. Several 35 millimeter cameras do not provide any accurate method of rewinding the film without causing the leading end of the film (the leader) to pass through the exit or passageway into the cassette. Once the leader is in the cassette, it is very difficult to retrieve it in order to process the film or to use any unexposed portions of the film at a later time.
This loss of the leader or leading end of the film occurs in two very different situations. When the roll of film has been completely photographically exposed, it is rewound into the cassette; and it is desirable to have the leader available to remove the film from the cassette for processing. If the leader is not available, the cassette can be broken open to allow removal of the film. While this approach can be somewhat difficult and inconvenient for both the amateur and commercial processor, it is a viable solution. This leader is also lost in the situation where the photographer has partially used a roll of film and desires to change to another type of film. The photographer must return the original film to the interior of the cassette; and, in doing so, the leader is often lost, i.e., moved to a position totally within the film cassette. If the photographer does not wish to waste the underexposed portion of the original roll of film, he must somehow retrieve the leader. He may, of course, break open the cassette, which must be done in a dark room, but in the process, often ruins the cassette so that the film cannot be used without obtaining a new cassette.
Some have attempted to obviate this problem by preventing the leading end of the film from being fully rewound into the film cassette in the first place. For example, the film cartridges disclosed in U.S. Pat. Nos. 3,695,160 and 3,705,696 are each provided with an integrally-molded projection, which is adapted to enter a perforation in an end of a filmstrip to thereby preclude its entry into a take-up chamber. See also U.S. Pat. Nos. 4,145,133 and 4,212,527, wherein the leading end of a filmstrip is disfigured in a manner to preclude its entry into a film cassette. Also, see U.S. Pat. No. 4,034,393 wherein a hook is secured to the leading end of the film to prevent its movement into a film cassette. While these proposed solutions may have certain attributes, they are subject to the criticism that they may result in the filmstrip being torn, or otherwise damaged, if one were to continue to try to rewind the filmstrip after it had been stopped; and, such continued rewinding may damage the rewinding mechanism of the camera in which the film is located.
Others have recognized the value of being able to retrieve the leading end of the film without ruining the film, the cassette and/or the camera. For example, U.S. Pat. No. 3,261,237 describes a tool which can reach into the film cassette and retrieve the leading end of the film. U.S. Pat. Nos. 3,864,993 and 4,047,653 describe similar tools. However, these tools require proper manipulation and are subject to being misplaced in the workshop.
As is well known, the leading end of a roll of 35 mm film is generally located outside of the film cassette such that it may be readily attached to the film advance mechanism of a camera. However, this increases the chances that the film may be prematurely exposed due to the leading end of the film being inadvertently pulled so as to withdraw a larger length of film than usual prior to the film being loaded into a camera. Another disadvantage in having the leading end of the film originally located exteriorly of the film cassette is that one or more layers of the film may be formed of a material, such as polyester film, which is capable of "lightpiping", i.e., transmitting light along its length so as to eventually fog an adjacent photosensitive layer. Accordingly, ambient light striking an exteriorly located leading end of a length of film would be transmitted by the polyester film to the interior of the film cassette where it may fog the photosensitive layer of the film. Thus, the intensity of the ambient light incident upon the light transmitting layer and/or the period of time of exposure to such light are factors which could result in the fogging of the film. For the above reasons, it may be advantageous to package the film with its leading end or leader located within the film cassette and to provide a simple means whereby the photographer may retrieve the leading end prior to loading the film into a camera.